1. Field of the Invention
The present invention generally relates to neurofeedback equipment and techniques. More particularly, the invention relates to the use of color in a neurofeedback system.
2. Background Information
For many years, neurologists, psychotherapists, researchers, and other health care professionals have studied the human brain. One commonly studied parameter is the electrical activity of the brain. Using electrodes adhered to a person's scalp in conjunction with associated electronics (amplifiers, filters, etc.), an electroencephalogram (“EEG”) is recorded over a given time period depicting the electrical activity of the brain at the various electrode sites. In general, EEG signals (colloquially referred to as “brain waves”) have been studied in an effort to determine relationships between frequencies of electrical activity or neural discharge patterns of the brain and corresponding mental, emotional and cognitive states. As a result of this type of work, it has become generally accepted that monitoring a person's EEG and providing feedback information to the person as a function of the EEG can actually serve to enable a person to voluntarily reach or maintain a target mental state and enhance performance in certain areas. This type of feedback technique is referred to generally as “neurofeedback.”
As a function of time, EEG signals appear to the untrained eye as seemingly random squiggles on a paper chart or display. Upon more careful inspection, the EEG signals typically follow a pattern of sorts, with peaks and valleys crudely approximating a sinusoidal waveform. The number of peaks of an EEG per second is referred to as the “frequency” and is measured in units of Hertz (“Hz”). The frequency of EEG signals vary from site to site on the head, and also vary as a function of the mental state of the person.
A standard has been used for many years to permit easy reference to EEG frequencies. Table I below shows eight standardized frequency bands and the typical mental state associated with each band.
TABLE IEEG DesignationsNameFrequency range (Hz)General Subjective StateDelta0–4Sleep, unconsciousprocessingTheta4–7 or 4–8Deeply relaxed, inwardlyfocusedAlpha8–12 or 8–13Very relaxed, passive attentionBeta>13External attentionSMR Beta12–15Relaxed, external attentionMid Beta15–18Active, external attentionHigh Beta18–35Anxiety, external attentionGamma>30 or >35Peak performance states or aconsolidation frequencyMore recently, practitioners have referred less often to the frequency bands by their Greek labels and more often to numerical range of the band (e.g., the “1–3 Hz” band). This is largely a result of many practitioners delineating the frequency bands differently.
Numerous neurofeedback techniques have been attempted over the years. Common to many of these techniques is the use of discrete visual or audible feedback signals or cues that relate in some predetermined manner to the person's EEG signals. These techniques typically compare the frequency of an EEG signal to a predetermined frequency threshold or frequency range and provide one visual feedback signal if the EEG frequency is within the range and a different feedback signal if the frequency is outside the range. The person being trained uses these feedback signals to modify the electrical activity of one or more areas of the brain thereby achieving a target mental state. Examples of such techniques are described in U.S. Pat. Nos. 5,024,235 and 5,899,867.
Although satisfactory to some degree in certain applications, such techniques are generally self-limiting in their ability to display the full range of frequencies at a wide variety of cortical sites in an intuitively easy to understand format. For example, in FIGS. 14–18 of U.S. Pat. No. 5,899,867 (U.S. Pat. No. 5,899,867 incorporated herein by reference in its entirety), a simplistic facial image is shown as the feedback image to the person. The face has two eyes, two eyebrows, a nose and a mouth. The mouth is controlled by the amplitude of the alpha waves (8–12 Hz), and the eyebrows are controlled by the theta wave (4–7 Hz) amplitude. As a form of neurofeedback therapy, this type of visual representation can be difficult for a patient to reconcile and process in a useful manner. Moreover, conventional feedback techniques typically require more of a conscious effort to focus on the task at hand and learn the format for very narrow control.
Additionally, conventional electrodes that are adhered to a person's scalp for neurofeedback therapy typically use a sticky conductive paste that is messy to apply and messy to clean up afterwards. Further, the time required to correctly position the electrodes and verify that a sufficiently low impedance exists between each electrode and the scalp is relatively long, and the process is generally inconvenient to the person being monitored.
Accordingly, an improved neurofeedback technique is needed, particularly one that avoids or minimizes the feedback issues noted above and the mess and inconvenience involved with adhesive-type electrodes.